title: Human immunoglobulin heavy chain genes: evolutionary comparisons of C mu, C delta and C gamma genes and associated switch sequences.
abstract: Human immunoglobulin heavy chain constant region genes have been characterised in isolated clones. The human c mu gene comprises discrete domains for C mu 1, C mu 2, C mu 3 and C mu 4 + tp separated by short intervening sequences. The C delta gene has been located about 5 kb downstream of C mu 4. Furthermore, the coding segments for the membrane form of mu have been located 1.9 kb downstream of C mu 4. Tandemly repeated sequences implicated in the heavy chain class switch occur upstream of the C mu and the C gamma genes, but none were detected near the C delta gene. These tandem repeats are very homologous to those of mouse. Particularly common is the sequence G-A-G-C-T. These data suggest that the mu to gamma switch in humans involves DNA rearrangements of the CH-genes and subsequent deletion of DNA, but that the coexpression of C mu and C delta genes results from different mechanisms.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D004274:DNA, Recombinant / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D009693:Nucleic Acid Hybridization
chemical_list: D004274:DNA, Recombinant; D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains